It’s been another tough year for water in America’s grain basket. This past week, one-quarter of the Midwest was in some state of drought, and drought covered nearly half of corn-growing areas in the U.S.. That’s largely due to recent “flash drought” conditions—extremely dry, extremely hot weather at the end of the summer that has sucked moisture out of the soil and offset what had been a relatively wet and cool start to the spring and summer growing season

Even if the hot and dry weather continues, conditions won’t be as bad as they were last year, when the U.S. was gripped by a historic drought that cost the country more than $50 billion. But as both the population and the economy continue to grow, demand for water—for agriculture, industry and personal use—will likely increase as well. Throw in the fact that climate change is likely to intensify dry periods in already arid parts of the country, and the need to be water-efficient will shift from a green option to a business imperative—especially if water is a basic ingredient in your product.

One such example: beer. More than 90% of the average beer is water, and additional water is needed to irrigate the growing barley and hops that go into your lager or ale. Many beer makers require as much as six barrels of water for every barrel of beer they brew. But in its new sustainability report (PDF), MillerCoors—which owns brands like Miller Lite, Coors and Molson—announced that it now uses a record-low of 3.82 barrels of water per barrel of beer, down 6.1% from the year before. And while the company has worked to cut water waste at the final brewing stage, most of that improvement comes from enhancing efficiency at the farm—which means their methods could help American farmers prepare for a drier future. “The entire brewing process is rooted in water and agriculture,” says Kim Marotta, the director of sustainability at MillerCoors. “It’s part of our DNA from the beginning.”

The best of those techniques are on display at the company’s showcase barley farm in Idaho’s Silver Creek Valley. It starts with irrigation, which in the U.S. is responsible for 37% of all freshwater withdrawals. Irrigation also consumes energy—you need electricity to pump water out of an underground aquifer and to spread it on your fields. Too often, though, farmers overirrigate, saturation bombing their fields with pumped groundwater. It’s not hard to see why—farmers are more concerned with ensuring their crops get all the water they need than they are in husbanding groundwater supplies, and there’s been little financial disincentive to using as much water as you think you need. The result: “More than 90% of the water used to produce beer comes in the agriculture supply chain,” says Marotta. “So the real change had to come with our ag partners.”

The Silver Creek farms in Idaho have managed to save a total of 270 million gallons of water between 2011 and 2012 by improving irrigation. Farmers converted 300 acres of flood-irrigated land—a simple and cheap method in which water simply flows along the ground among the crops—to sprinkler irrigation. Such precise, drip by drip irrigation can cut the amount of water used by 75% while improving soil productivity and reducing fertilizer runoff to nearby waterways. (Less water flowing in the field means less runoff.) More efficient irrigation requires less pumping, which means less energy use—the showcase farm managed to cut energy usage from $50 per acre to no more than $22.

MillerCoors has also worked to improve energy efficiency while brewing and bottling, reducing the size of the nozzles on equipment and cutting the duration of the sprays used to clean cans and bottle fillers. Other MillerCoors breweries reused and recycled water in the cooling system and eliminated unnecessary rinse cycles to cut water waste. But the lesson here is that it’s at the farm where the battle over water will really be fought—especially in the West, where thirsty farms are increasingly competing for water with growing cities. California has experienced the driest year to date on record, and the federal government has had to cut water releases from the Colorado River—which feeds states throughout the West—to all-time lows.

Water has always been underpriced and underappreciated, but as with the climate, the indifference is beginning to change. Whether you’re brewing beer, baking bread or making microchips, you won’t always be able to count on free and unlimited supplies of water. In a dry world, efficiency will have to become the norm.